I have checked the thread about the referred subject. However, I cannot find the gdk in /etc/sysconfig. I am a novice so please advise me in detail. I have fedora12 i686.

Have you checked your desktop options at the login window?

I have automatic login.

There are other way which I don't know, but at login window I think you have the option to select different desktop sessions

when you login to ur desktop(gnome) then try to run : system-config-display, may this will help.....
or
u can also go to run level one and then try ur to manipulate ur bash files to prevent autologin......

Being autologin, I get Gnome dekstop automatically, I dont know what to do? I had heard that the KDE has better graphics.

Do you have...

Assuming that you have all the Fedora repositories enabled, have you downloaded and installed the packages that are needed for KDE? If you installed Fedora with Gnome, Fedora will not automatically have provided more than what is required for that desktop.

Check your list of available package and the packages that are now installed, then you should see if you can use KDE.

If you don't set up your boot to require a log-in, you can boot, then do a log-out, log-in again, and you should be able to choose between any installed desktops.